What doesn't make sense? I have Givi Monokey racks on my VFR. I plan on mounting a Givi Monokey plate to whatever rack I put on the EX500. At that point, I can mount the existing bags I've got on either bike as needed. I'm not sure where you got the idea that I'm trying to get a rack that will switch between bikes.
I know Givi isn't currently (and thus never will) making a mounting kit for the EX500, but something like a Renntec rack would allow me to put a monokey plate on the rack, giving me the ability to put the bags I already have on the bike.